The influence of activator treatment on skeletal growth in Angle Class II: 1 cases. A roentgenocephalometric study.

The aim of this study was to evaluate possible skeletal effects of activator treatment on children with Angle Class II:1 malocclusions. The material consisted of lateral roentgenocephalograms of 31 girls and 22 boys, 8-14 years of age, who were treated with Andresen activators for an average period of 2.5 years. Growth and treatment effects were determined by comparing measurements on cephalograms of a group of untreated children with the same facial morphology and growth rate. The cephalograms were superimposed on the sella-nasion line and on the internal structures of the mandible. The activator treatment had a significant effect on the sagittal intermaxillary relationship and the anterior facial height. Among the girls the decreased ANB angle was mainly due to a retarded forward growth of the maxilla, while this decrease among the boys depended more on increased mandibular growth. Another feature was the anterior rotation of the mandible in the activator subjects although to a lesser extent than in the control groups. The total amount of condylar growth did not differ between the groups, but the direction of growth did. In the activator groups the growth was in a more superior-posterior direction than among the controls, thus contributing to the increased total length of the mandible in the activator groups.